The SRVDxSkinAdapteк (DrawEditorFrame = True) does not change Srv.BackgroundProperty.ColorBegin ...ColorEnd, but Srv is painted according to DevEx Skin, but the ZoomPanel does not change the background color (because Srv.BackgroundProperty.ColorBegin ...ColorEnd not changed)
To change the background of the ZoomPanel I do the following
...
if Assigned(RootLookAndFeel.SkinPainter) then
begin
AColor := RootLookAndFeel.SkinPainter.DefaultControlColor;
BackgroundProperty.ColorBegin := AColor;
BackgroundProperty.ColorMiddle := AColor;
BackgroundProperty.ColorEnd := AColor;
// but this changes the ZoomPanel background three times (TSRVZoomPanel.Paint)
end;
...
What is the best way to change ZoomPanel background color - ?

Sorry for the delay.
Yes, a zooming panel is drawn using BackgroundProperty's gradient colors (even when a gradient fill is turned off, it is drawn using ColorBegin).
So your changes are correct.

However, for some skins results are not the best, because a zooming panel uses system (or VCL theme) colors for drawing text, lines and highlighting buttons.
In the next update, SRVDxSkinAdapter will change these colors as well.